Annealing apparatus



Oct. 7, 1930. L. L. LEWIS 1,777,978

. ANNEALING APPARATUS Filed Dec. 2, 1929 "FIB-J.. FIRE- L J LESTERLLEWIS;

out through the seal.

practice.

Patented Oct. 7,1930

UNITED STATES- PATENT .OFFICE LESTER L. LEWIS, OF NEW CASTLE, PENNSYLVANIA, AS SIGNOR T0 BLAIR, STRIP STEEL COMPANY, OF NEW CASTLE, PENNSYLVANIA A CORPORATIONIOF PENNSYLVANIA ANNEAIJING APPARATUS Application filed December 2, 1929. Serial No. 411,179.

This invention relates to improvements in apparatus for heat treating metal for largely eliminating discoloration-and increasing its ductility,'and has as its essential object material improvement in the results obtained as compared with those secured by standard Under standard practice, it is customary to enclose work to be annealed in a housing and introduce the housing into the furnace where the work is raised to the requisite temperature for the necessary period of time, both varying accordin to the character of work and other control ing factors, and, after the heating operation, the housing with the enclosed work is withdrawn from the furnace and allowed to cool before the work is removed from the housing. It is known to be desirable to' av0id access of air to the work during the heat treatment and while cooling of the work, and, to this end, it has been the practice to provide a seal of comminuted material along the line of jointure between separable parts of the housing, and after the housing and its contained work have been removed from the furnace efforts have been 'made'to restrict access of alrto the work whll-e coollng b introducing natural gas into the housing un er pressure sufficient to penc-' trate the seal from the interior and to work While this has been supposed .to exclude air, I have observed oxygen discoloration and carhon'deposits on the work as a practically invariable and expected result, showing that some air has found access to the interior of the housing and that sufficient combustion has occurred for releasing the carbon in the natural gas. While I am not fully informed as to all the detrimental action occurring incident to the disturbing Y of the seal by the introduction of gas under pressure to the interior of the housing and the exhausting of such gas through the seal, I have observed in addition to the carbon depositsv and oxygen discoloration of the work a substantial limit to the degree .to which the work will draw, that is, its ductility is limited.

The ductility is greater and the discoloration,

less when the natural gas under pressure is introduced and caused to percolate through the seal during the cooling operation than when no gas is used, and I conclude, therefore, that the provision for internal pressure acting outwardly materially aids in excluding air from access to the housing, but does not fully succeed, and a certain amount of air still finds its way into the housing despite the pressure and movement of the gas from terial increase in ductility of the metalannealed; the substantial decrease in the cost of production, and the marked improvement in the surface appearance and condition of the treated work.

With these and other objects in view as will in part hereinafter become apparent and in part be stated, the invention comprises apparatus best adapted for practically wholly precluding access of air to the interior of .the work-containing housing during treatment or while cooling.

- The invention comprises certain novel con- .structions, combinations, and arrangements of parts especially well adapted for the annealing of work to agreater ductility and freer from discoloration than heretofore known, all as will hereinafter be set forth and subsequently pointed out in the appended claims.

In the accompanying drawings,

Figure 1 is a fragmentary plan view of a furnace and work-containing housing of the type to which the present invention appertains. v

Figure 2 is a transverse section of the housing detached and taken on the plane indicated by line 22 of Figure 1, the parts being seen on an enlarged scale. Figure 3 isa top plan view of the parts seen in Figure 2, parts of the cover aligle for the gas pipe being broken away.

Figure 4 is an enlarged, detailed, fragmentary section similar to a part of Figure 2.

Figure 5 is a further enlarged, detailed, fragmentary elevation of the gas pipe and cover angle detached.

Referring to the drawings bypumerals, 1 indicates any well known or standard type of annealing furnace having the usual ball or roller tracks 2 for facilitating movement of a, tray 3 thereon into and out of thefurnace 1. The tray 3 is of standard construction well known 1n the industry, and is preferably provided with guiding grooves 4, 4, for receiving the balls or like rollers 2 so as to direct movements of the tray 3 and allow the tray to be moved readily into and out of the furnace.- Thetray 3 is formed with upstanding flanges 5 bordering the complete margin of the tray so as to provide a relatively deep receptacle. It is standardpractice to place work, such as indicated at-6, 6,

on the tray 3 which forms part of the housmore or less.

left room enough below the plane of the .Would recommend filling ing for the work, and to complete the lionsing by covering the work with a hood 1 which is commonly referred to in shop par-f lance as a pot?. The pot 7 and tray 3 are ordinarily heavy castings and it is standard practice to place a bed or seal 8 of comminuted material-such as iron filings or sand on the upper surface of tray 3 all about the work 6 before the pot 7 is lowered into the space surrounded by the flange 5, and the margins at the open under face of the pot 7 rest in and cause the sand to be compact and to provide a seal against access of air to the work 6. It is also common practice, after the pot 7 has been lowered over the work to enclose the same and to rest on the sand bed 8 to further guard against ingress of air by packing sand at 9 all about the lower portion of the pot 7 outward to the flange 5 until the space between the pot and flan e is completely filled and effectively tampe According to the present invention, however, I do not completely fill the said space but prefer to leave about one-third of the space unfilled; that is to .say, with a tray 3 having a flange 5 of ten inches in width I the space within flange 5 and about the pot 7 for a height of about six inches, although some variation in the height is, of course, allowable, and the-fill may vary from five inches to seven inches, At all events, there should be upper edge of the flange 5 to accommodate the parts to'be inserte therein as now to be described. But for t e fact of failure to completely fill the space'between pot 7 and flange 5 and the fact that no tube is inserted through the seal 8, so that the seal 8-remains undisturbed, the parts are introduced into the furnace 1 as in standard practice, and the .der pressure to the interior of the housing madeup of pot 7 and tray 3. Such a tube is commonly inserted through the sand seal before the housing is introduced into the furnace 1, and gas under pressure is connected to the tube and discharged therethrough as soon as the housing is withdrawn from the furnace for cooling. The gas used in such standard practice invariably contains moisture, and while it has been proposed and attempted to eliminate the moisture by heating the gas and passing it through a carbon bed for absorbing the moisture, I am unaware of any instance where all ofuthe moisture has been successfully eliminated, and, therefore the gas which is thus introduced in standar practice into the housing carries with it certain elements destined to injuriously affect the work 6. It is true, of course, that before the use of the introduced gas the results were much poorer than obtained. by the use of the gas, and it has been popularly supposed and is probably true that the supply of gas under pressure within the housing largely protects the, work 6 against ingress of air through the sand seal during the cooling operation, both because of the presence of the gas under pres-.

sure and because the pressure on the gas is great enough to cause it to penetrate the sand and act as a reagent against the ingress of air. But notwithstanding the superior re-- sults of the standard practice of the use of natural gas or like gas under pressure in the housing as compared with results previously obtained without the gas, the results secured ?y the use of the gas are far from perfect and cave much to bedesired both because of sur-' face discoloration, carbon absorption, and relatively low degree of ductility resulting in the work when so treated.

According to the present invention, no gas is introduced directly into the housing, and: the sand seal 8 is maintained undisturbed. After the housing has been subjected to the correct temperature for the.

proper period of time within furnace 1,'it

is moved out along the track 2 and allowed to stand the necessary time for cooling down. However, according to the present invention, as quickly as practicable after the withdrawal of the housing from the furnace 1, a gas coil is located in the space surrounded by the flange 5 outside of pot 7 and gas similar to that above described is delivered through openings in the gas coil. The coil may consist of one or more layers of pipe and may and preferably will be covered with sand. As seen in the accompanying drawing, the gas coil preferably consists of a pipe 10 which, for facility of assemblage and removal, is divided up into two sections, one occupying one-half and the other the other half of the space about pot 7 be low the upper margin of flange 5. Pipe 10 is provided with jet openings 11 in sufficient number to insure a uniform distri-. bution of gas about the part 7.

An angle plate bafile 12 is preferably arranged above pipe 10 and spaced therefrom, as by supporting lugs 13, 13, resting on pipe 10 and fixed to angle plate 12. The angle plate 12 serves as a baflie and the jets 11 cause the gas to be projected within the angle of the plate 12 and to be spread by the plate toward both sides of the space in which the parts appear. Thus, the discharging gas envelopes the entire area surrounding pot 7 and enclosed by flange 5 beneath the upper edge of said flange. I prefer to place loose sand on top of the baflle or angle 12 and to fill the space above said angle to the level of the flange 5. A sufficient amount of sand should be introduced above bathe 12 to insure against being blown out by gas pressure, and to aid in the distribution of the gas across the space between the pot 7 and the flange 5 so as to resist air pressure tending to cause seepage of air toward the interior of the pot The pipe or coil 10 is located in proper position, as described, as quickly after the removal of the work-containing housing from the furnace 1 .as practicable, and the gas is turned on so as to provide a gas seal supplcn'lenting the sand seal 8. Of course, the high temperature of the surrounding parts will cause ignition of the gas, but that does not prevent the action of the gas in supplementing and protecting the seal. Furthermore, the pressure caused by the gas, whether ignited or not, is generally upward and is sufficient to counteract or prevent the tendency of air to seek access through the seal 8, and, therefore, the cooling of the work 6 progresses to completion without the presence of air or of carbon-forming substances within the housing, except such as may be present from the lubricant used in rolling, and it is preferable, when best results are to be secured, to employ as the rolling lubricant a'non-carbonaceous fluid. However, as the treatment of metal, and particularly iron and steel, when rolled by a non-carbonaceous vehicle as a lubricant, is the subject of a separate invention which I have produced and on which I propose to file a patent application, and since effective results may be secured by the present invention notwithstanding the presence of a small amount of carbonaceous rolling vehicle on the work, further consideration of the treatment of the work prior to its introduction into the annealing housing is not here required. It may be noted, however, that carbon spots are always likely to occur on the surface of any work annealed after having been rolled with the aid of the usual oil or like carbonaceous vehicle, unless the surface of the work is wiped or otherwise effectively cleaned before the work is subjected to annealing.

It should be understood, of course, that the present improved apparatus is effectively available for use with any metal requirin annealing, but is particularly effective with. rolled iron and steel, and I have observed a very marked difference and superiority in the annealed product when treated according to this invention as distinguished from the standard practice, which superiority includes superior surface conditions and appearance and a. very substantial increase in ductility.

The time for cooling, of course, will vary with different conditions and bulk of work and size of pot, and I have observed that work which has been in the furnace from sixteen to twenty hours in a relatively small pot, say five-ton capacity, will ordinarily require from twenty-four to forty hours for cooling, and the gas should be maintained under pressure and supplied to the pipes it) constantly until the cooling operation has been completed, and the operator is ready to lift the pot 7. The degree of pressure for the gas will be substantially the same as that heretofore employed for introduction of gas to the interior of the pot 7 and should sufliciently exceed an atmosphere to provide effective discharge of the gas for the supplementing sealing action above indicated. It should be observed also that while a single pipe line 10 is shown, a plurality of such pipes superimposed may be employed as additional precaution for preventing access of air through seal 8. It is, of'course, well" ,known that during cooling of the work the tendency to form a vacuum within the pot creates a suction, or, in other words, creates an unbalanced condition relative to atmospheric pressure. It is in Y theory that the present invention efl'ective y precludes access of air by the reactive force of the discharging gas; and it is entirely possible, even probable, that portions of the gas discharged from pipe 10 find their way through the comminnted seal into the pot, but it is not my intention according to the apparatus or preferred method of use of such apparatus comprising the present invention to directly introducethe gas to the interior of the pot. It should be obvious that any gas finding its way into the pot will not injuriously afl'ect the contained work because the intense heat. of the comminuted material forming the seal through which the gas must pass, and also the intense heat of contiguous parts of the pot and tray will free the gas from discoloration agents and render it a neutral gas so far as action on the contained work is concerned. In the o eration of the apparatus described, when t e pot is initially lowered over the work, a certain amount of air and other discoloration agents are liable to be present within the pot, and some of them remain even after the heating operation. During the heating operation, expansion of contained air and moisture causes the elimination of a large proportion of the thus contained discoloration agents by seepage through the comminuted seal even though no other exit is provided, so that, when the pot is removed from the furnace, only a comparatively small amount of discoloration agents remains, and the discoloration resulting therefrom is negligible, manifestin itself usually in the form of blued edges. he balance of the work and frequently a lar e portion of the edges are absolutely brig 1t and free from discoloration.

While the seal for the housing has been illustrated and described as located at the bottom or lower portion thereof and as being formed of sand, iron filings or like comminuted material, it is well known and common practice to construct annealing housings with the seal at the top or otherwise located, and the present invention is equally applicable to seals so located and also to seals made of other materials than those stated.

The art or process disclosed herein is made the subject matter of claim in my co-pending application Serial No. 479,051, filed August .30, 1930.

What is claimed is 1. In apparatus for annealing, the combination, with a housi having separable spaced parts adapted to e sealed during use,

of a seal for the joint between the parts, and

means exterior of one part of the housing for discharging gas within the body of the seal.

2. In annealing apparatus, the combination, with a housing having separable parts lapping each other and spaced apart, of a seal located between the lapped parts, and means for delivering gas between the lapped parts within the seal, and a baflle for spreading the gas across the space between the lapped parts.

3.111 annealing 'apparatus, the combination, with a housing having separable parts lapping each other and spaced apart, of a seal located between the lapped parts, a gas supply pipe located between the lapped arts and having discharge openings,and a afile above the discharge openings located to spread gas emanatin from said pipe across the space between sai lappedparts.

4. An annealing apparatmomprising a housing having spaced and lapped parts, a seal in the space between the lapped parts, a gas supply pipe within the seal, and means for covering the gas supply pipe extending substantially across the space between the lapped parts. I

5. In apparatus for annealing, the combination, with a housing having separable parts adapted to be sealed during use, of a seal for the'joint between the parts, and means for delivering to within the body of the seal an agent neutral to the work being annealed.

6. In apparatus for annealing, the combination, with a housing having separable parts adapted to be sealed during use, of a comminuted seal for the joint between the parts, and means for delivering a gas to within the comminuted material of the seal.

7. In apparatus for annealing, the combination, with a housinu adapted for containing work to be anneziled and for cooling in the open air while containing such work, said housing including separable parts adapted to be sealed during use, of a comminuted seal for said parts, and means for delivering a gas to within the comminuted material of the seal under pressure sufficient to distribute the gas within the comminuted material of the seal against external air pressure.

8. In apparatus for annealing, the combination, with a housing having separable parts, one of said parts engaging the other along a margin substantially surrounding the housing, of a comminuted seal equally substantially surrounding the housing and sealing the joint between said parts, and a gas delivery pipe located within the comminuted material of the seal and substantially surrounding the housing and having discharge means for delivering gas about the housing within the seal.

9. In apparatus for annealing, the combination, with a housing having separable parts adapted to have a seal extend along the joint between the parts, of a comminuted seal for said joint, and means for delivering gas to within the body of the comminuted seal along the full length of the same.

10. In apparatus for annealing, the combination, with a housing comprising a tray and an annealing pot thereon, of a seal for the joint between the tray and pot, and means for discharging gas into the body of the seal.

11. In apparatus for annealing, the combination, with a housing having separable parts adapted to be sealed during use, of a seal for the joint between the parts, and a gas supply pipe arranged within the body of the seal and having openings for discharging gas within the seal.

In testimony whereof I aflix my signature.

LESTER L. LEWIS III) 

